There is a gap in the market for PVC jacketing for cable compounds that can pass CSA's FT4 vertical flame test, but at the same time can have the flexibility and a very low brittle point, said Michael Roberts, industry manager for the vinyl division of Teknor Apex.

The compound was designed specifically to pass the UL 1685 Vertical Tray test and Canadian Standards Association's FT-4 Vertical Tray Flame Test.

Flexalloy 9614-73 elastomer is a 73 Shore A compound that is UV-stabilized and exhibits a brittle point of -65°C or below. “So what's new is really achieving that balance of properties in one compound,” he said. “It took us over a year of dedicated R&D to create a compound.”

The reason creating this compound was difficult was because those properties are working against each other, Roberts said. Typically, the more flame retardant a compound is, the more brittle the product becomes, and the softer the material is, the more flammable it is.

“So balancing those three properties that are working together is very challenging,” Roberts said. “And what it enabled the cable maker to do is really have a very soft, flexible compound that can be used in all sorts of high performance applications, particularly in the colder regions of Canada.”

While the elastomer is available globally, he said it is really focused on the North American market. The Flexalloy product line has many products, but customers were asking for a step change in performance around cold temperature and flexibility. “We took that customer feedback, and that's really what guided our development,” Roberts said.

Flexalloy PVC elastomers are proprietary formulations that provide the elasticity and low-temperature toughness of thermoplastic elastomers, plus the many benefits of PVC, the company said. “Typically to achieve this type of performance, you're not able to use a PVC material,” he said. “You have to use a more expensive polymer. ... Those materials, you know, can be between 50-300 percent more expensive than a PVC-based elastomer.”

The vinyl division of Teknor Apex produces other compounds based on PVC, including flexible and rigid vinyl, Flexalloy vinyl elastomers, BioVinyl compounds with bio-based plasticizers and Fireguard low-flame, low-smoke compounds for wire and cable.